Allow configuring max commits in gitlab module

[Juho Vanhanen]

Gitlab module has hardcoded limit of 3 commits, please allow user to configure this setting.

CptHook/input/gitlab.go

Line 392 in c4b081c

 if pushEvent.TotalCommits > 3 { 

[Felix Breidenstein]

Hi,

never thought about it, but yes, this is a good thing to put into the configuration.